Keyboard Shortcuts
ctrl + shift + ? :
Show all keyboard shortcuts
ctrl + g :
Navigate to a group
ctrl + shift + f :
Find
ctrl + / :
Quick actions
esc to dismiss
Likes
- TekScopes
- Messages
Search
|
Re: Digitizer on eBay
ghpicard
--- In TekScopes@y..., "Miroslav Pokorni" <mpokorni2000@y...> wrote:
I believe that those digitizers were used to measure all sorts ofparameters during test, so a number of them was consumed for a single test. Myremember I think it's more probable that the units could reliabily withstand just one EMP, so why to risk a second EMP with a total data loss when you could buy a new one... If the unit become damaged *during* the test, the data, if you could recover anything at all, would be either garbage or unreliable at all. Memory circuits (except perhaps ferrite cores) are most sensitive to gamma rad. Anyway, if using ferrite cores, the M part of the EMP could make a nice mess with the contents... Regards Gaston |
|
Re: Digitizer on eBay
ghpicard
--- In TekScopes@y..., "Miroslav Pokorni" <mpokorni2000@y...> wrote:
I believe that those digitizers were used to measure all sorts ofparameters during test, so a number of them was consumed for a single test. Myremember I think it's more probable that the units could reliabily withstand just one EMP, so why to risk a second EMP with a total data loss when you could buy a new one... If the unit become damaged *during* the test, the data, if you could recover anything at all, would be either garbage or unreliable at all. Memory circuits (except perhaps ferrite cores) are most sensitive to gamma rad. Anyway, if using ferrite cores, the M part of the EMP could make a nice mess with the contents... Regards Gaston |
|
Re: Who's up to some remote troubleshooting?
Craig Sawyers
I don't have a copy of the 7A26 schematic, so this is a *real* stab in the
toggle quoted message
Show quoted text
dark. How long are the triggering events that you're looking for? I fooled myself for a day recently while trying to fix my HP counter when I was convinced that the input section wasn't working I was feeding it with a 1kHz square wave, and could see nothing at all on the bus lines coming from the differetial line driver on that card. The reason? The output was a 5ns duration ECL pulse at the trigger transitions of the input wave (as set up by the trigger level controls). Once I triggered on the event, and then sped the scope sweep up - there it was! Interestingly (and very tackily) this is generated by using three ECL NORs in a loop, and the output pulse duration is generated by the differential pulse delay of two gates - or about 5ns for 10xxx series ECL. Now since many of the y-amp 7000 series plug ins use custom silicon (as well as the timebase), and much of this fast custom silicon is ECL-based, are you sure that there isn't a triggering event there but of a non-intuitive time duration? Cheers Craig -----Original Message----- |
|
Who's up to some remote troubleshooting?
Lynn Lewis
I plan to get back to this after lunch today. Any suggestions would be
appreciated. It's not life or death, just my idea of fun. Item: 7A26 with serial number B2.... Setup: This 7A26 is in a 7704 with a known good 7B53A. I am feeding both channels, not necessarily at the same time, from the 1KHz square wave calibrator. I started at .04V but have worked up to 4V. I'm using a 7904 to see the waveforms. The 7B53A is set to use the internal trigger. Symptom: Can not sync through channel B using internal trigger. If both channels are receiving square wave, it syncs. If channel A only is receiving square wave, it syncs. If channel B only is receiving square wave, it will not sync. Knowns: 1. I have another 7A26 that works perfectly in that same bay so it's not the scope and it's not the 7B53A. 2. If I feed the square wave only into channel B, I can use the other scope and follow it right up to U2750. The input pins to U2750 have the square wave (fuzzy but square). The output pins do not (fuzzy and flat). (Note: If I feed the square wave only into channel A, I can see it on both the input and output of U1750.) The DC voltages around U2750 are very close to those indicated on the schematic and appear to me to be reasonable. I did resistance checks on the resistors in the input network to U2750. 3. I have tried: a. replacing U2750 twice b. replacing U1750 c. replacing Q920, Q940, Q960, and Q980. Suggestions: |
|
Re: On screen display and other CRT items....
I also recall, vaguely, something about some adjustments in some 7K mainframesUnfortunately, the IC vertical designs don't have a thermal compensation adjustment. Again, the 7904 is an example, and my 7904s do suffer from swimming readouts. |
|
Re: 7603 lights, and more about transient protection
Miroslav's comments about neon lamps in the older supplies asSome of the supplies have spark gaps as well as neon lamps - an example is the 7904. I'm not sure if they are to protect the scope from the power line, or to protect the power line from the scope's HV in case of disaster. |
|
Re: Question about 7603
Stan or Patricia Griffiths
The 040-0686-01 mod kit for 7600 series plugin lamps uses an LM309K between +8
toggle quoted message
Show quoted text
volts in the mainframe and +5 delivered to the plugin compartments for lamp power. Derating of the range of acceptable line voltages and operating temperature of the scope are required if the total plugin lamp current exceeds 1.5 amps. You just add up the lamp current requirements of each plugin to see if it exceeds 1.5 amps to know if you have to derate line voltage or temperature specs. The total kit instructions are on 7 pages of microfiche and installation instructions and a parts list are included along with a derating chart. I can provide hard copies of the instructions for 50 cents per page plus $1 for postage (total = $4.50). Stan w7ni@... david@... wrote: Is the 7603 supposed to light up the buttons on the plug-ins? Some of myThere is a listing in the catalog for the 040-0686-01 "lights power supply |
|
Re: On screen display and other CRT items....
The company I work for has sold custom flat panel displays to another major
US test equipment manufacturer (use your imagination here). About 5 years ago, their info said their analog scope CRT life historically was between 40-80K hours typical. This discussion was in the context of concern regarding CFL backlight life of AMLCD flat panel displays, which was about 10K hours back then (to 50% of initial brightness). They did not want to get in a situation of having to replace backlights mulitiple times during the life of the instrument, when this wasn't an expectation for the analog CRTs, but I digress. Assuming Tek tube life is similar to the stated CRT life mentioned above, one would burn up a tube in roughly 4 to 8 years if the instrument was left on all the time. For that reason, plus the benefit of saving power (something not all that abundant as was shown this last summer) and life of other parts like electrolytic caps, I tend to shut everything off when not in use, or when I won't be back to it for more than a couple hours. I've had a 2465A at work for 13 years now, and even when it's on, if I'm not using it for a short bit, I will put the scope in single shot mode to shutoff the beam and readout. It still has a very healthy CRT despite starting life as a rental instrument. Hopefully, when used only when needed, the instrument will last a lifetime :>) My Heathkit 25" TV, with brightness and contrast used in moderation, has lasted so far 19 years. Perhaps too long according to my wife.... Don |
|
Miroslav: re ESR meter [via 7D01 discussion]
Ashton Brown
Miroslav Pokorni wrote:
Your point noted.. as I haven't gotten around to using the meter - can't say how many caps are marginal. There's a good discussion of the subtleties in following links, incl. limits of mere ohms or capacitance 'checks': ESR meter info: Some more comments about usage: I ordered from Vancouver BC: A different (analog) meter - w/schematic refs As to the Dick Smith kit - I concluded it was cheaper and a lot handier to not reinvent the wheel. Good qual. parts and it worked precisely as described. Anyone with Heathkit experience would achieve same, of course. I haven't tried the hints re small batteries - mentioned in a link below, but it might be useful on odd PS problems in micro-sized devices (hearing aids?) My problem is making the time to troubleshoot a variety of Teks (incl. a few 485s and one 'chirping'!) - whereas I spent my time mostly using scopes.. not in their more subtle repair. Some of the arcane problems which say, the Z-axis board can cause.. stress my more Boolean effforts :( And if a 335 is clockmaking - a 2xx is watchmaking! See what you think of the Dick Smith Special. IIRC schematic is on one or more of these sites. Cheers, Ashton Brown (ex-LBL - particle accelerators. Tons of Tek everywhere!) |
|
Re: I found a nice 7CT1N :-)!
Richard W. Solomon
I also have one of these Plug-Ins. Now I also need to figure out how to make
toggle quoted message
Show quoted text
it work !! BTW, I have a 7D01 plug-in, but condition unknown. Someday I'll plug it in and see if it works. (I had the manual, but sold it.) 73, Dick, W1KSZ -----Original Message-----
From: JOSE V. GAVILA (EB5AGV/EC5AAU) [mailto:eb5agv@...] Sent: Monday, January 21, 2002 1:57 AM To: TekScopes@... Subject: [TekScopes] I found a nice 7CT1N :-)! Hello my friends, As saying says, 'early bird gets the worm'! I start working at 7:00AM... yes, I know it is early in the morning. But it has its advantages: I stop working at 3:05PM (so I have lots of time for other things, including family, hobbies :-), extra works, ...). Also, I am able to look at late at night listed auction items (specially those at eBay Germany and eBay UK) very early. This time, there was a 'Buy It Now!' Tektronix 7CT1N curver tracer. It was not too cheap, I must admit (US$180), but it seems in perfect cosmetic shape and comes with manual. And it is in Germany, so there is no Customs to Spain and shipping is not expensive :-) I have been looking for that curve tracer for a while so I am very happy to have located one. Now I 'just' need to explain it to my wife... but this is another story ;-) I would appreciate any hints about operating that plug-in. Regards, JOSE ---------------------------------------------------------------------- 73 EB5AGV / EC5AAU - JOSE V. GAVILA La Canyada - Valencia (SPAIN) EB5AGV Vintage Radio Site: European Boatanchors List: To unsubscribe from this group, send an email to: TekScopes-unsubscribe@... Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. |
|
7603 lights, and more about transient protection
wshawlee2
No, the plug in lights to NOT light in a 7603 frame, this was
intentional, but I don't know the orignal thinking that led to it. 7A26 and similar format vertical plug ins don't need it, and the 7B53A (the intended sweep plug in) has white indicator rings around the pushbuttons, and NO internal lights. so, if yours doesn't light, that's just what it's supposed to do, but the rationale is now lost to history. Miroslav's comments about neon lamps in the older supplies as transient protection are not correct, they were warning indicators for lethal voltage, nothing more. This is even explained in the service manuals. Older unit have no AC transient protection. Tek really should have incorporated transient protection with it's switchers, as many were designed before rugged high voltage FETs existed, and they are easily damaged by transients. I was not suggesting you buy a crappy $4.95 trasient protector, as I use some very high end ones here, but it's up to you. Tek (after many field failures) added this protection to later 2200 series units, and it seemed to help significantly, they were just single ordinary GE varistors. If you are really in love with your gear, by an autocorrecting Liebert UPS, the ultimate in line conditioning. Leaving it on vs. turning it off. well, this argument has raged for decades, but I think you need to consider some simple math: the 7K series runs VERY hot, and it has some definite MTBF limits associated with capacitor and semiconductor failures caused by this, not to mention consuming the CRT. if you leave it on, you are wasting 2/3 of that MTBF at night, and when no one is around. I get the thermal shock argument, but my own long standing experience is that this is an order of magnitude less of a problem than burning the equipment for endless hours. It makes no difference to me what other people do, but to me, the wasting of so much equipment life is silly, and serves no purpose whatsoever. When the tube is gone, you can't exactly whittle one from a block of wood, so think it over carefully. I have often thought of putting a small NTC or other surge limiter in series with the filament to reduce thermal shock, but interestingly, the overwhelming failure mode I have seen from Tek CRTs is going weak or gassy, NOT filament failure. What do you suppose that means? Not good statistical support for leaving it on, that's for sure. all the best, walter |
|
Re: On screen display and other CRT items....
Stan or Patricia Griffiths
The only two Tek scopes that I can remember having more than one power switch
are the 507 and 517 and I don't really recall what the real story was on those. I think they were separate switches for filament and DC power. I don't recall anything like a "standby switch". One other reason you might not want to keep your scope turned on all of the time is that tubes in distributed amplifiers develop cathode interface over long hours of on time. The only answer to cathode interface is to retube the amplifier. In order the "save the CRT" it has also been suggested to simply turn down the intensity to cut off the CRT beam current. In the case of some of the 560 series, I understand that even if there is no visible display on screen, the CRT cathode may be emitting anyway. This is because some scopes used a scheme of driving the beam off screen during retrace time so it was not visible, rather than actually shutting down the CRT gun. I can't be more specific about model numbers because this is all from my weak, 63 year old, memory . . . I also recall, vaguely, something about some adjustments in some 7K mainframes to minimize things like readout jitter due to thermal heating of the vertical position stages when the vertical has to make large and rapid changes in beam position due to going from displaying readouts on screen to switching way off screen to a trace way above or way below the screen. This is another "weak" memory of mine. Maybe Dean has more on this . . . Stan w7ni@... |
|
Re: Question about 7603
Michael
Is the 7603 supposed to light up the buttons on the plug-ins? Some of mybut no light emerges....I remember reading somewhere that the 7000 plugins were designed to be lit, but the poor reliability of the bulbs and the difficulty in changing them caused Tek a rethink and the idea was scrapped. Dunno if this is correct. (mine don't light either). :-( Michael |
|
Re: Question about 7603
Is the 7603 supposed to light up the buttons on the plug-ins? Some of myThere is a listing in the catalog for the 040-0686-01 "lights power supply for 76XX mainframes", but I haven't been able to find out anything about it. I wonder if this existed because the 76XX +5V supply doesn't have enough reserve to run the lights with some combination of plugins, or if it provided the intensity switch that most mainframes have. (I always run mine on the lower intensity setting because I hate changing the *&*$#@ lamps.) Does anyone have any details on this kit? |
|
Re: Question about 7603
Hi Craig,
toggle quoted message
Show quoted text
my 7603 doesn't do it either. The backplane has two empty pins, where you could connect some 5V source. I thought about connecting that to the stabilized +5V and to ground. Finally i didn't do it, because i didn't know whether the power supply has enough power on that line to drive all the lamps. Regards Dieter Craig Sawyers wrote: Hi folks |
|
Re: Price of Tubes
Phil (VA3UX)
Don't feel bad about that one Craig. $132 for a pair of 12AU6 - matched
toggle quoted message
Show quoted text
Tektronix or not - is foolishness. That's got to be the audio guys again. Phil At 07:28 AM 1/21/2002 +0000, you wrote:
I'm astonished! |
|
Re: Price of Tubes
Craig,
toggle quoted message
Show quoted text
You can call that 'e-bay syndrome'. I have seen 7000 series plug ins reaching $150 while there were similar ones with $10 opening bids without bidders. Regards Miroslav Pokorni ----- Original Message -----
From: "Craig Sawyers" <c.sawyers@...> To: <TekScopes@...> Sent: Sunday, January 20, 2002 11:28 PM Subject: [TekScopes] Price of Tubes I'm astonished!I thought that given the price of NOS RCA 12AU6's here in the UK is around???4 each that I'd be happy to pay around $15 for a pair of Tek ones.$132.50!!!
_________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at |
|
Price of Tubes
Craig Sawyers
I'm astonished!
I was bidding on a NOS pair of Tek 12AU6 tubes on eBay - a matched pair. Nice for my Type L plug in (didn't really need them, but good insurance). I thought that given the price of NOS RCA 12AU6's here in the UK is around ???4 each that I'd be happy to pay around $15 for a pair of Tek ones. I was rapidly disabused of that notion - they went eventually for $132.50!!! Craig |
|
Re: Digitizer on eBay
I believe that those digitizers were used to measure all sorts of parameters
toggle quoted message
Show quoted text
during test, so a number of them was consumed for a single test. My understanding was that they were lowered down the hole, but somehow digitizers lived until data was transmitted to a safe location. I remember talking with Tektronix salesman in Orange County who was covering company that I worked for and, must have been, EGG also. Much later in time, I found out that EGG was a major contractor for Nevada site and frequently a front company for ordering long lead time supplies. In that conversation I was lamenting about problems of failures in field and Tek guy laughed and said how he never gets service calls, just another order. He never said who was his customer, I guessed that after reading about testing. There also seems to have been test parameters recorded photographically from screens of 7903, blue phosphor and reduced deflection options. I bought one of those to cheaply get hold of 7A19s; guy was selling those scopes for less money than asking price for a single 7A19, at the time, and would not hear of selling just plug ins. I had to take the whole thing; something like Stan's venture in government auctions. The camera mount adapter was hard bolted to scope frame. I have never seen something like that before: the screws that hold CRT in place were replaced with longer ones so that camera mount adapter was grabbed, too. I guess, camera falling of the scope was not considered an acceptable event. Guy who was selling those 7903s would bring two or three at the time to swap-and-meet at the TRW. He was probably hoping that tea-spooning would hold up price, but he did not have many takers. I saw him asking $450 for a scope, two pieces of 7A19 and 7B80 and after several months at the other swap-and-meet asking price was down to $250. I am pretty inept at bargaining, but I got a unit for $200. The 7A19 were option WF, something not shown in a Tek catalog; comparing physical unit with description in catalog makes WF a recessed control mod. In the case of 7A19 it was trace position that was recessed; there was no trace ID, either, but that must have been incidental to recessed control. The mainframe (7903) was also WF option and that was intensity control that was recessed. Time base was kind of a standard unit, though serial number indicated Guernsey (numerals only). Regards Miroslav Pokorni ----- Original Message -----
From: "Stan or Patricia Griffiths" <w7ni@...> To: <TekScopes@...> Sent: Tuesday, January 15, 2002 10:42 PM Subject: Re: [TekScopes] Digitizer on eBay Lynn,. . when you need to catch the EMP on your screen.like a Tek part number on it? Is it a rackmounted item with a hinged door onthe front?need actuallyto go with it to make it useful? onbought it for the box ($5 + S&H) shippingthe list a few days ago. There is one listed on eBay, item 1690813203 costs to the UK would be astronomical. |
to navigate to use esc to dismiss